1. Field of the Invention
The invention relates to touch-sensitive input and output devices, and more particularly, to touch screens that simultaneously can display a keyboard-type image superimposed on a background image. The invention also relates to other features of touch-sensitive i/o devices. Embodiments of the invention have particular application to wearable-computing devices and environments, although non-wearable embodiments are also contemplated.
2. Description of Related Art
It is known in the art to superimpose a keyboard over an image that is output by an application being executed on a computer, i.e. to form a "phantom" keyboard, on a touch-sensitive input display device. U.S. Pat. No. 5,581,243 to Ouellette et al., for example, which is incorporated by reference herein in its entirety, describes a system for displaying a simulated keyboard on a touch-sensitive display, without occluding from view an underlying application output image. An output image is generated and displayed for a first period of time at a first luminous radiation intensity having a predetermined persistence. A simulated keyboard image is generated and displayed for a second, shorter period of time at a second, lower luminous radiation intensity having the predetermined persistence. The keyboard and output images are generated in alternation, and the amount of time each is displayed is controlled, to try to create the illusion that both images are being displayed continuously.
The system described in Ouellette et al., however, is believed to suffer a number of disadvantages. First, it is believed that flashing between application and keyboard screens, as the reference discloses, would significantly reduce the refresh rate achievable relative to a continuously displayed application output (or a keyboard) image. This reduction could cause considerable detriment to the viewer and potentially could confuse the displayed interpretive features. Second, it is believed that displaying the keyboard and the application output in alternation requires additional hardware features for proper functioning, for example a second frame buffer for switching back and forth between the screens. Additionally, although this feature is not disclosed or apparently contemplated in Ouellette, using the Ouellette device in a wireless-transmission (e.g. RF) environment, for example in a wearable-computing context, would require e.g. twice as much information to wirelessly be transmitted and therefore would greatly increase the required bandwidth.